1. Field of Invention
The present invention relates to image-capturing equipment, and in particular, to a lens actuation device, optical system, and camera.
2. Related Art
The control of the lens portion is critical to the image quality. Through the control and adjustment of the positions of the lens, the zoom, focus, and vibration reduction functions, and the like of the camera lens may be achieved. Currently, the lens drive normally adopts the electromagnetic actuation manner. FIG. 1 is a three-dimensional exploded view of a conventional lens actuation device adopting electromagnetic actuation. The lens actuation device includes a housing consisting of an upper case 701 and a lower case 702. A carrier 1 with hollow middle portion is disposed in the housing, and the lens is fixedly installed in the carrier 1. A magnet 2 and a coil 3 are arranged around the carrier 1, and the coil 3 is fixed (connected) to the carrier 1. Flat springs 601, 602 are respectively disposed between the carrier 1 and the upper and lower cases 701, 702. The magnet 2 and coil 3 constitute the electromagnetic transducer functioning for actuating the carrier 1, and after being powered on, the electromagnetic transducer converts the electromagnetic energy into the mechanical force, and thus the carrier 1 can be driven by the coil 3 to adjust the movement of the lens.
In the above structure, the magnetic field intensity of the magnet attenuates quickly, which results in the non-uniform distribution of the magnetic field in space. Therefore, the following deficiencies are inevitably caused. (1) In the course of the movement of the mount, the action force of the magnetic field applied on the coil is non-uniform, which causes the difficulty in effectively controlling the movement of the mount. (2) Due to the attenuation of the magnetic field intensity, in order to sustain a stable action force of the coil and magnetic field, the current needs to be increased, and consequently the power consumption increases.